Relationship of warfarin versus DOACs with thrombogenic milieu in the left atrium among patients with nonvalvular atrial fibrillation

Background Thrombogenic milieu (TM) within the left atrium plays a pivotal role in the pathogenesis of thromboembolic events, for which anticoagulation treatment is indicated typically on the mandatory basis. Little is known, however, about which regimen of anticoagulation, warfarin or direct oral anticoagulants (DOACs), is more likely associated with TM. We evaluated relative relationship of the two treatment options with concurrently-observed TM in patients with nonvalvular atrial fibrillation (AF) who underwent transesophageal echocardiography. Methods TM was defined as the presence of either left atrial spontaneous echo contrast (SEC) or thrombus, or both. To determine which regimen was more likely related to TM, we firstly compared the prevalence of TM in 208 patients taking warfarin (Warfarin group) versus 486 patients taking DOACs (DOAC group); and secondly, did the same analysis after propensity score matching. Results Warfarin group was more likely associated with TM compared with DOAC group (46% vs 29%, p < 0.001). Similar findings were observed for dense SEC (18% vs 7%, p < 0.001) and thrombus (4% vs 1%, p = 0.057). The propensity score matching (198 patients for each group), where several baseline parameters were matched including age, gender, chronicity of AF, estimated glomerular filtration rate and B-type natriuretic peptide as well as the left ventricular ejection fraction, resulted in similar findings to the original groups (TM, 47% vs 32%, p = 0.002; dense SEC, 18% vs 7%, p = 0.001; thrombus, 4% vs 1%, p = 0.047). Conclusions This study may strengthen the data on randomized trials that DOACs are superior to warfarin in preventing thromboembolic events in nonvalvular AF patients. Further studies are required to elucidate the details behind this difference.